You Block An Egress

"a place or means of going out : exit"
Driveways, parking lots, cross and side streets all can be considered an egress.  When you're on the travel portion of the roadway you should be aware of these.  Of course if the traffic is moving you should also, but when you're stopped, usually in a line of cars, at a red light or stop sign, courtesy would dictate that you stop far enough back to allow a car to exit.  Conversely if you're the 2nd or 3rd car trying to exit it would be discourteous of you to block or unnecessarily delay the driver on the roadway who is being courteous.   Just before a red light on a street that I often travel there is a sign that says, "don't block driveways."  Most drivers block them anyway.  I think that if in the driveway there was a small cannon with an electric eye with a timer, of say 10 seconds, and if a car was in the line of fire for that time period it would blast the car off the road.  Then courtesy might just be in vogue.